The present invention relates to a detachably attachable moving headboard trailer ejector and floor cleaning apparatus for use with a self-unloading trailer having a front end, a rear end, side walls, and either a reciprocating slat conveyor floor or a conveyor belt floor. The invention comprises, in one embodiment, a base, a panel sweeper, one or more panel sweeper support members, a means for traversing the panel sweeper, a tether bar, side flanges, and a base flange. In use, the invention is placed in the front end of a self-unloading trailer and the trailer is loaded with material; when material is ejected from the trailer, the invention transverses or “travels” along the top of the moving floor and pushes the material out of the trailer's back end. The rubber flanges ensure a snug fit within the trailer and keep post ejection residual material at a minimum.